Vulcanization of Butyl Rubber by p-Quinone Dioxime

1978 ◽  
Vol 51 (2) ◽  
pp. 267-277 ◽  
Author(s):  
L. M. Gan ◽  
G. B. Soh ◽  
K. L. Ong
Keyword(s):  
Chemical Reactions ◽  
Crosslinking Density ◽  
Butyl Rubber ◽  
Oxidizing Agent ◽  
Red Lead

Abstract The vulcanization of butyl rubber by p-quinone dioxime oxidized by red lead and tetrachloroquinone was investigated. The maximum physical effective crosslinking density of the vulcanizates appeared to be when p-quinone dioxime and the oxidizing agent were equimolar. The formation of one physical effective crosslink required one molecule of p-quinone dioxime. Chemical reactions are suggested for the vulcanization steps.

Vulcanization Reactions in Butyl Rubber. Action of Dinitroso, Dioxime, and Related Compounds

1946 ◽  
Vol 19 (4) ◽  
pp. 900-914 ◽  
Author(s):  
John Rehner ◽  
Paul J. Flory
Keyword(s):  
Natural Rubber ◽  
Chemical Reactions ◽  
Active Agent ◽  
Butyl Rubber ◽  
Nitroso Compounds ◽  
Cross Linking ◽  
Oxidizing Agent ◽  
Nitroso Group ◽  
Oxidizing Agents ◽  
Related Compounds

Abstract Experiments have been carried out to determine the chemical reactions that occur when Butyl rubber is vulcanized by quinone dioxime or related compounds. Observations have been made of the reactions of these substances with simple olefins, and of the effect of oxidizing agents on the dioxime-type of vulcanization of Butyl in solution. The theory is proposed that, in the vulcanization of Butyl by quinone dioxime or its esters, in presence of oxidizing agents, the active agent is p-dinitrosobenzene formed by oxidation of the dioxime. Chemical reactions are suggested for the subsequent cross-linking or vulcanizing steps, and the results of confirmatory experiments are presented. p-Dinitrosobenzene and other polynitroso compounds are active vulcanizing agents for Butyl, natural rubber, Buna-S, Buna-N, and Neoprene, and do not require the addition of an oxidizing agent. It is suggested that vulcanization of natural rubber by polynitro compounds involves their reduction to corresponding nitroso compounds as the first step, and that the nitroso group adds to rubber to produce cross-linkages.

Quinoid Curing of Butyl and Natural Rubbers

1983 ◽  
Vol 56 (5) ◽  
pp. 883-891 ◽  
Author(s):  
L. M. Gan ◽  
C. H. Chew
Keyword(s):  
Crosslink Density ◽  
Butyl Rubber ◽  
Red Lead

Abstract The vulcanization of butyl and natural rubbers by p-dinitrosobenzene (DNB), p-quinone dioxime (GMF) and p-quinone dioxime dibenzoate (dibenzo GMF) oxidized by various oxidants was investigated. Good curing efficiency (E=1.2) was achieved for a butyl system containing GMF or dibenzo GMF oxidized by red lead (Pb3O4). It was estimated that about 85% of the combined quinoid agent was in the form of crosslinks and the remaining 15% might be present as pendant groups. In contrast to butyl rubber, NR could also be cured slowly by GMF or dibenzo GMF alone. Simple ZnO or PbO was effective in activating dibenzo GMF to produce quinoid-NR vulcanizates with good scorch safety. But the highest crosslink density was obtained from equimolar dibenzo GMF/Pb3O4. Low crosslinking efficiency (E=3–6) was generally observed in the quinoid-NR systems. Quinoid vulcanization mechanisms are discussed. The crosslinks consist mainly of the anil structure in the butyl system, while azoxy crosslinks might also be present in the NR system.

Heats of Vulcanization of Synthetic Rubbers

1944 ◽  
Vol 17 (2) ◽  
pp. 404-411 ◽  
Author(s):  
P. L. Bruce ◽  
R. Lyle ◽  
J. T. Blake
Keyword(s):  
Carbon Black ◽  
Natural Rubber ◽  
Chemical Reactions ◽  
Side Reaction ◽  
Heat Evolution ◽  
Butyl Rubber ◽  
Vulcanized Rubber ◽  
Principal Reaction ◽  
Low Sulfur ◽  
Quantity Of Heat

Abstract 1. The heats of vulcanization for natural rubber and Buna-S are nearly equal. The data for both materials indicate two different chemical reactions during vulcanization. At low sulfur percentages, the principal reaction forms soft vulcanized rubber and is accompanied by little or no heat evolution. Above the 2 per cent sulfur region, a second reaction predominates, forming hard rubber and producing a relatively large quantity of heat. 2. The presence of an accelerator (Santocure) in Buna-S has little, if any, effect on heat of vulcanization. 3. The addition of carbon black to Buna-S lowers the heat of vulcanization in the region above 4 per cent sulfur. The calories evolved in a 10 per cent sulfur compound decrease linearly with percentage of carbon black. 4. The heats of vulcanization of Buna-N (Hycar OR-15) indicate the presence of two chemical reactions. Unlike natural rubber and Buna-S, the ebonite reaction does not predominate until the sulfur concentration is raised above 10 per cent. 5. The heat of vulcanization of Butyl rubber with sulfur is equal to the heat evolved with natural rubber containing 0.6 per cent sulfur. If one sulfur atom reacts per double bond, the maximum amount combining would be 0.72 per cent sulfur. During the vulcanization of Butyl rubber with p-quinone dioxime and lead peroxide, a large amount of heat is evolved by a side reaction between the vulcanizing agents. The reaction involving the Butyl rubber produces about 6 calories per gram, a considerably higher value than the 1 calorie produced by sulfur vulcanization. 6. The heat of vulcanization of Neoprene-GN without added agents corresponds to a value for smoked sheet rubber containing 4.5 per cent sulfur. The addition of zinc oxide and magnesia decreases the heat of vulcanization.

scholarly journals Butyl Rubber-Based Composite: Thermal Degradation and Prediction of Service Life Time 

2019 ◽  
Author(s):  
Phuong Nguyen-Tri ◽  
Ennouri Triki ◽  
Tuan Anh Nguyen
Keyword(s):  
Polymer Network ◽  
Life Time ◽  
Crosslinking Density ◽  
Butyl Rubber ◽  
Metalworking Fluids ◽  
Effect Of Temperature ◽  
Service Lifetime ◽  
Metalworking Fluid ◽  
Rubber Composite ◽  
Different Temperatures

Butyl rubber-based composite (BRC) is one of the most popular materials for the fabrication of protective glove against chemical and mechanical risks. However, in many working places such as metal manufacturing or automotive mechanical services, its mechanical hazards usually appear together with metalworking fluids (MWFs). The presence of these contaminants, particularly at high temperature, could modify its properties due to the scission, the plasticization, the crosslinking of polymer network and thus led to severe modification of mechanical and physicochemical properties of material. This work aims to determine the effect of temperature and a metalworking fluid on mechanical behavior of butyl rubber composite dealing with crosslinking density, cohesion forces and elastic constant of BRC on the based on Mooney-Rivlin’s theory. The effect of temperature with and without MWFs on thermo dynamical properties and morphology of butyl membranes is also investigated. The prediction of service lifetime is then evaluated from extrapolation of Arrhenius plot at different temperatures.

scholarly journals Butyl Rubber-Based Composite: Thermal Degradation and Prediction of Service Lifetime

2019 ◽  
Vol 3 (2) ◽  
pp. 48 ◽  
Author(s):  
Phuong Nguyen-Tri ◽  
Ennouri Triki ◽  
Tuan Anh Nguyen
Keyword(s):  
Arrhenius Plot ◽  
Polymer Network ◽  
Crosslinking Density ◽  
Butyl Rubber ◽  
Metalworking Fluids ◽  
Effect Of Temperature ◽  
Service Lifetime ◽  
Metalworking Fluid ◽  
Rubber Composite ◽  
Different Temperatures

Butyl rubber-based composite (BRC) is one of the most popular materials for the fabrication of protective gloves against chemical and mechanical risks. However, in many workplaces, such as metal manufacturing or automotive mechanical services, its mechanical hazards usually appear together with metalworking fluids (MWFs). The presence of these contaminants, particularly at high temperatures, could modify its properties due to the scission, the plasticization and the crosslinking of the polymer network and thus lead to severe modification of the mechanical and physicochemical properties of material. This work aims to determine the effect of temperature and a metalworking fluid on the mechanical behavior of butyl rubber composite, dealing with crosslinking density, cohesion forces and the elastic constant of BRC, based on Mooney–Rivlin’s theory. The effect of temperature with and without MWFs on the thermo-dynamical properties and morphology of butyl membranes was also investigated. The prediction of service lifetime was then evaluated from the extrapolation of the Arrhenius plot at different temperatures.

Vulcanization of Butyl Rubber: Curative Effects of 2-Pentadecylbenzoquinonedioxime

1981 ◽  
Vol 54 (4) ◽  
pp. 692-697 ◽  
Author(s):  
N. D. Ghatge ◽  
N. N. Maldar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Butyl Rubber ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Rubber Vulcanizate ◽  
Aging Study ◽  
Red Lead ◽  
Good Retention

Abstract The structure-property relationships of butyl rubber vulcanizates derived from quinonedioxime-red lead or quinonedioxime-MBTS-sulfur cure systems were studied. The effects of the dioxime curatives on the mechanical properties of the elastomer are discussed on the basis of rheological and heat-aging study. It was found that a 2-pentadecylbenzoquinonedioxime-MBTS-sulfur cured butyl rubber vulcanizate shows good retention of tensile strength on heat aging at 125°C.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

Surface reactions observed by photoemission electron microscopy (PEEM)

1992 ◽  
Vol 50 (1) ◽  
pp. 286-287
Author(s):  
H.H. Rotermund
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Work Function ◽  
Chemical Reactions ◽  
Reaction Diffusion ◽  
Dynamic Processes ◽  
Clean Surface ◽  
Crystal Surfaces ◽  
Single Crystal Surfaces ◽  
Photoemission Electron

Chemical reactions at a surface will in most cases show a measurable influence on the work function of the clean surface. This change of the work function δφ can be used to image the local distributions of the investigated reaction,.if one of the reacting partners is adsorbed at the surface in form of islands of sufficient size (Δ>0.2μm). These can than be visualized via a photoemission electron microscope (PEEM). Changes of φ as low as 2 meV give already a change in the total intensity of a PEEM picture. To achieve reasonable contrast for an image several 10 meV of δφ are needed. Dynamic processes as surface diffusion of CO or O on single crystal surfaces as well as reaction / diffusion fronts have been observed in real time and space.

Microwaves: Application in Electron Microscopy

1990 ◽  
Vol 48 (3) ◽  
pp. 140-141
Author(s):  
Anthony S-Y Leong ◽  
David W Gove
Keyword(s):  
Electron Microscopy ◽  
Light Microscopy ◽  
Chemical Reactions ◽  
Electromagnetic Waves ◽  
Tissue Fixation ◽  
Primary Method ◽  
Dipolar Molecules ◽  
Wide Range ◽  
Time Required ◽  
Cryostat Sections

Microwaves (MW) are electromagnetic waves which are commonly generated at a frequency of 2.45 GHz. When dipolar molecules such as water, the polar side chains of proteins and other molecules with an uneven distribution of electrical charge are exposed to such non-ionizing radiation, they oscillate through 180° at a rate of 2,450 million cycles/s. This rapid kinetic movement results in accelerated chemical reactions and produces instantaneous heat. MWs have recently been applied to a wide range of procedures for light microscopy. MWs generated by domestic ovens have been used as a primary method of tissue fixation, it has been applied to the various stages of tissue processing as well as to a wide variety of staining procedures. This use of MWs has not only resulted in drastic reductions in the time required for tissue fixation, processing and staining, but have also produced better cytologic images in cryostat sections, and more importantly, have resulted in better preservation of cellular antigens.

Fine structure and properties of defects in naturally occurring silicates and oxides

1990 ◽  
Vol 48 (4) ◽  
pp. 460-461
Author(s):  
David R. Veblen
Keyword(s):  
Chemical Reactions ◽  
High Resolution Electron Microscopy ◽  
Extended Defects ◽  
Single Chain ◽  
Naturally Occurring ◽  
Resolution Electron ◽  
Fine Structures ◽  
Image Simulations ◽  
Similar Crystal Structure

Extended defects and interfaces control many processes in rock-forming minerals, from chemical reactions to rock deformation. In many cases, it is not the average structure of a defect or interface that is most important, but rather the structure of defect terminations or offsets in an interface. One of the major thrusts of high-resolution electron microscopy in the earth sciences has been to identify the role of defect fine structures in reactions and to determine the structures of such features. This paper will review studies using HREM and image simulations to determine the structures of defects in silicate and oxide minerals and present several examples of the role of defects in mineral chemical reactions. In some cases, the geological occurrence can be used to constrain the diffusional properties of defects.The simplest reactions in minerals involve exsolution (precipitation) of one mineral from another with a similar crystal structure, and pyroxenes (single-chain silicates) provide a good example. Although conventional TEM studies have led to a basic understanding of this sort of phase separation in pyroxenes via spinodal decomposition or nucleation and growth, HREM has provided a much more detailed appreciation of the processes involved.

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